/*
 * Copyright 2011 Daniel Drown
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * dns64.c - find the nat64 prefix with a dns64 lookup
 */

#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <strings.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#include "dns64.h"
#include "logging.h"
#include "dhcpcd-files/memory.h"

/* function: plat_prefix
 * looks up an ipv4-only hostname and looks for a nat64 /96 prefix, returns NULL on failure. caller frees pointer returned
 * ipv4_name - name to lookup
 */
struct in6_addr *plat_prefix(const char *ipv4_name) {
  struct addrinfo hints, *result, *p;
  int status;
  struct in6_addr *plat_addr, this_plat_addr;
  struct sockaddr_in6 *tmpaddr;

  plat_addr = NULL;

  bzero(&hints, sizeof(hints));
  hints.ai_family = AF_INET6;
  status = getaddrinfo(ipv4_name, NULL, &hints, &result);
  if(status < 0) {
    logmsg(ANDROID_LOG_ERROR,"plat_prefix/dns(%s) status = %d/%s\n", ipv4_name, status, gai_strerror(status));
    return NULL;
  }

  for(p = result; p; p = p->ai_next) {
    if(p->ai_family != AF_INET6) {
      logmsg(ANDROID_LOG_WARN,"plat_prefix/unexpected address family: %d\n", p->ai_family);
      continue;
    }
    tmpaddr = (struct sockaddr_in6 *)p->ai_addr;
    this_plat_addr = tmpaddr->sin6_addr;
    this_plat_addr.s6_addr32[3] = 0;

    if(plat_addr) {
      int i;
      for(i = 0; i < 4; i++) {
        if(plat_addr->s6_addr32[i] != this_plat_addr.s6_addr32[i]) {
          char tmpaddr[INET6_ADDRSTRLEN], tmpaddr2[INET6_ADDRSTRLEN];
          logmsg(ANDROID_LOG_ERROR,"plat_prefix/two different plat addrs = %s,%s",
              inet_ntop(AF_INET6, plat_addr, tmpaddr, sizeof(tmpaddr)),
              inet_ntop(AF_INET6, &this_plat_addr, tmpaddr2, sizeof(tmpaddr2))
              );
          free(plat_addr);
          return NULL;
        }
      }
    } else {
      plat_addr = xmalloc(sizeof(struct in6_addr));
      *plat_addr = this_plat_addr;
    }
  }
  freeaddrinfo(result);
  return plat_addr;
}
